1. Field of the Invention
The present invention generally relates to a personal authentication device for conducting a personal authentication by using information concerning an object inside a living body and an image input device implementable as an object image input means of the personal authentication device.
2. Description of the Related Art
Recently, a personal authentication device has been mounted to a mobile phone, a notebook personal computer, other various information processing devices. In minimizing the information processing device, it is required to further minimize the personal authentication device to mount to the information processing device.
For example, Japanese Laid-open Patent Application Publications No. 2004-272821 and No. 2005-092375 disclose an personal authentication device using a vein pattern of a finger. The personal authentication device uses an optical system of a single eye, and limits an object distance and an image pickup distance to optically form an image. Accordingly, it is limited to further minimize a size and reduce a weight of the personal authentication device.
Moreover, Japanese Patent No. 3705766 discloses an image input device combining a micro lens array, a color filter, a photo acceptance unit array, and a like.
In a case of a personal authentication device using information concerning an object inside a finger such as the vein pattern of the finger, it is required to cohere the finger to the device. The image input device used for the personal authentication device has a particularity of picking up an image of the object being considerably closed.
In a case of using a finger print, necessary information of a finger print pattern can be acquired by picking up an image of a narrow area of the finger. On the other hand, in a case of using a finger vein, it is required to pick up an image of a wider area of the finger in order to acquire necessary vein pattern information. In order to observe an image of the object in a considerably closer state, an equi-magnification imaging with a micro lens array is generally used. However, if attempting to pick up an image of a wider area by using the equi-magnification imaging, an imaging device having a wider imaging surface is required and a device cost is increased. An imaging surface of a CMOS (Complementary Metal-Oxide-Semiconductor) imaging device or a CCD (Charge-Coupled Device) imaging device, which is generally used and cheap, is limited. Accordingly, it is required to specially produce to obtain an imaging device having a wider imaging surface.